I tried but failed to find here a similar problem like mine. I have a problem when exporting InDesign file (book layout) as an Epub fixed layout. I tried to open an exported file on Kindle Previewer 3, and everything looks fine for me, but the client has a problem previewing with KDP Online Previewer. Fonts are "messy" and joined. I used Cambria Regular, Italic and Bold in the book, as well as Droid Sans in some places. Don't know which font is free to use and is there any list with font names I can use with Epub and Amazon ebook?
I've attached screenshot problems and if someone could help me that would be great. Thank you in advance for help!
Moving to InDesign EPUB forum